Process for producing water insoluble polymers of n-vinyl imides



3 322,730 PRQCESS FOR PRODIZICING WATER INSOLUBLE POLYMERS F N-VINYlL HMIDES Frederick Grosser, Midland Park, and Eugene V. Hort and Arthur Schwartz, Metuchen, N.J., assignors to General Aniline & Film Corporation, New York, N.Y.,

a corporation of Delaware No Drawing. Filed Oct. 23, 1963, Ser. No. 318,181 22 Claims. (Cl. 260--78) The present invention relates, in general, to nitrogenvinyl polymers and, in particular, to insoluble polymers of cyclic N-vinyl imides and methods of making the same.

Nitrogen vinyl polymers and particularly N-vinyl imides of the cyclic types have heretofore been polymerized by a variety of methods. Usually successful polymerization of N-vinyl imides depends to a great extent upon the purity of the starting material. In any event, however, it is known that pure N-vinyl imides polymerize readily under the influence of light, heat or peroxide catalysts, providing, in most cases, high softening polymers which are tough, readily swollen by, and in some instances soluble in, water and rather unstable. For example, Hanford and Stevenson, in US. 2,276,840 polymerized N-vinyl succinimide in aqueous suspension with benzoyl peroxide as a catalyst for a period of ten minutes at a temperature of 85 C. to produce a dry granular powder. The poly N-vinyl succinimide was swollen readi- 1y by water, acetone or alcohols and was soluble in phenols, dimethyl formamide, dilute mineral acids and organic aliphatic acids. Thus, while the polymers were generally characterized by high softening points making them admirably suited for certain end uses, their water susceptibility and solubility in common organic solvents limited their usefulness to those areas where water susceptibility and solubility in common organic solvents were not of primary concern. Thus, for example, polymers based in N-vinyl imides which are insoluble would find immediate and general applicability for use as beverage clarifiers, components of filter bed packings, complexing agents, dye receptors and plastic film uses, to name but a few. Thus, it is apparent that a need exists for polymers of N-vinyl imides and methods of producing the same, which are insoluble in common organic solvents and which are not swollen or soluble in water.

Accordingly, .it is an object of this invention to provide insoluble polymers of N-vinyl imides.

Another object of this invention resides in the provision of novel methods for producing insoluble polymers of N-vinyl imides.

Yet another object of this invention resides in the provision of insoluble polymers of N-vinyl imides which are not swollen by water and which are not soluble in common organic solvents.

Further objects and advantages of the invention will become further apparent from the following detailed description thereof.

It has now been discovered that significant increases in yields of polyvinyl imides are obtained by methods which comprise heating a mixture comprising an N-vinyl imide, a polymerization catalyst, hereinafter more fully described, and water at a first elevated temperature for a period of timesufiicient to induce incipient polymerization and forthwith cooling said mixture to a second temperature lower than said first temperature and maintaining said mixture at said second temperature until polymerization is complete.

The amounts of water which have been found useful in achieving the objects of the invention can vary from as little as 1.0 weight percent and lower to as much as 70 weight percent based on the weight of the N-vinyl imide charged to the reaction vessel. Beneficial results are ob- 3,322, Patented May 30, 1967 tained by employing amounts of water in the range of from 5 weight percent to about weight percent based on the N-vinyl imide and is, therefore, preferred. Either distilled or ordinary fresh water may be used.

The N-vinyl imides which are amenable to the polymerization methods of this invention can be conveniently represented by the following general formula:

C 0 2 in where R and R represent hydrogen and alkyl groups and n represents a whole positive integer of 1 through 4 and wherein all carbon atoms are tetravalent.

Representative N-vinyl imides within the scope of the general formula above which can be employed as starting materials to produce insoluble polymers are set forth in the following Table I:

TAB LE I l H II 1 CH3 H 1 CH CH3 2 CH3 CH3 2 Csllg H 3 H CH3 3 CH3 CH3 3 C 211 CH3 4 CH3 CH 4 H CH 3 4 II Calla 4 H Cally 4 C3117 CH3 Typical N-vinyl imides which can be employed as starting materials in the methods of the invention include:

-vinyl malonimide; N-vinyl succinimide; N-vinyl glutarimide; N-vinyl maleimide; N-vinyl-fl-methylglutarimide; N-vinyLa-amylsuccinimide; and N-vinyl adipimide.

The classes of catalysts which have been found efiective in promoting the polymerization of N-vinyl imides include corresponding oxides and hydroxide of the alkali metals and the alkaline earth metals. Alkali metals and alkaline earth metals which may be mentioned include sodium, potassium, lithium, rubidium, cesium, calcium, magnesium, strontium and barium. Oxides and hydroxides of alkali and alkaline earth metals which function as catalysts for the polymerization system include sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, barium oxide, calcium oxide and the like. Mixtures of oxides or hydroxides of different alkali and alkaline earth metals can also be employed.

The amount of catalyst necessary to efieet polymerization of the N-vinyl imide is not necessarily a critical feature of the invention and can be varied over a wide range of from about .05 weight percent to 5.0 weight percent, based on monomer, although amounts above and below this range can be employed if desired. An amount of catalyst of about 1.0 weight percent provides an optimum of reaction rates and reaction times and is therefore preferred.

The polymerization can be effected by heating the N-vinyl imide over a wide range of temperature of from about 40 C. to about 200 C. under subatmospheric, atmospheric or superatmospheric conditions, as desired.

The reaction periods usually will vary considerably depending upon a variety of factors, such as catalyst, cat- 3 alyst concentration, the temperature employed, and the like. Usually polymerization varies over a period of from one to about three hours. When polymerization does start, it is normally completed within about ten minutes.

In carrying out the methods of the invention, an N-vinyl imide is charged to a reaction vessel equipped with a stirrer, reflux condenser and the thermometer. The selected catalyst is charged at the same time or shortly thereafter. The contents of the reaction vessel are preferably purged with nitrogen gas or any other inert gas and the pressure on the reaction medium reduced and heat applied. Normally the contents of the reaction vessel are preferably agitated with the stirrer and the material maintained at reflux. After polymerization has been initiated the liquid N-vinyl imide will turn to a powder within about ten minutes. The product is then recovered by any conventional means, such as by filtration, whereupon it is Washed and dried.

The following examples will serve to further illustrate the practice of the invention with greater particularity although it is to be understood that the invention is not limited thereto.

Example 1 To a one-gallon autoclave were charged 360 grams of N-vinyl succinimide, 3.6 grams of 50% aqueous sodium hydroxide and 52 milliliters of distilled watenThe charge was heated and maintained at 140 C. for one hour, after which it was allowed to cool to 100 C., then maintained at that temperature. A rise of 6 C. was noted three To an autoclave were charged 360 grams of N-vinyl succinimide, 15 grams of 50% aqueous sodium hydroxide and 110 milliliters of distilled water. The mixture was heated and maintained at 130 C. for two hours, after which it was allowed to cool. At 75 C. the temperature rose 7". There was provided insoluble polyvinyl succinimide in a yield of 97% of theory.

Example 3 To a small citrate type glass pressure flask were charged 36 grams of N-vinyl succinimide, 0.72 gram of 50% aqueous sodium hydroxide and 3.5 milliliters of water. A magnetic agitator was inserted, the flask was purged with nitrogen and sealed. The flask was heated in an oil bath while the contents were stirred magnetically. A temperature of 135 C. was maintained for two and a quarter hours after which the oil bath was allowed to cool. When the temperature of the oil bath reached 85 C., there was a rise of 4 C. At the same time, the agitator was stopped due to the solidification of the mixture. Within thirty seconds the mixture was completely polymerized, and the flask was packed tightly with polymer. There was provided insoluble polyvinyl succinimide in a yield of 95% of theory.

Example 4 To an autoclave were charged 360 grams of N-vinyl succinimide, 5 grams of 50% aqueous potassium hydroxide and 51.5 milliliters of distilled water. The charge was heated and maintained at 140 C. for one hour, allowed to cool then maintained at 100 C. After one-half hour at 100 C. a temperature rise of 8 C. was noted. The mixture was then treated as in Example 1. There was provided insoluble polyvinyl succinimide in a yield of 95% of theory.

While the invention has been described in its various embodiments and specifically illustrated in the examples with respect to certain methods for polymerizing N-vinyl imides and novel catalyst combinations useful therefor in achieving one or more objects of the invention, it is apparent that the invention is not subject to restriction thereto since obvious modifications thereof will occur to persons skilled in the art. Therefore, it is intended that the invention shall include all such modifications and be interpreted as being applicable thereto insofar as the state of the art permits.

What is claimed is:

1. An improved method for the polymerization of N-vinyl imides to produce polymers thereof which are not soluble in water, which comprises heating a mixture comprising an N-vinyl imide corresponding to the formula:

C0 B1 IIzC=CHN (3/ wherein R and R represent hydrogen and alkyl groups and n represents a whole positive integer of 1 through 4 and wherein all carbon atoms are tetravalent, in the presence of a catalyst selected from the group consisting of the oxides and hydroxides of alkali metals and alkaline earth metals and water in an amount of from 1.0 to weight percent based on the weight of the N-vinyl imide, at a first elevated temperature and forthwith cooling said mixture to a second temperature lower than said first temperature and maintaining said mixture at said second temperature until polymerization is complete.

2. The method according to claim 1 wherein the N- vinyl imide is N-vinyl succinimide.

3. The method according to claim 1 wherein the N- vinyl imide is N-vinyl glutarimide.

4. The method according to claim 1 wherein the N- vinyl imide is N-vinyl-p-rnethylglutarimide.

5. The method according to claim 1 wherein the N- vinyl imide is N-vinyl-u-amylsuccinimide.

6. The method according to claim 1 wherein the N- vinyl imide is N-vinyl adipimide.

7. An improved method for the polymerization of N- vinyl imides to produce polymers thereof which are not soluble in water, which comprise heating a mixture comprising an N-vinyl imide corresponding to the formula:

wherein R and R represent hydrogen and alkyl groups and n represents a whole positive integer of 1 through 4 and wherein all carbon atoms are tetravalent, in the presence of a catalyst selected from the group consisting of the oxides and hydroxides of alkali metals, alkaline earth metals and water in an amount of from about 5 to 4-0 Weight percent based on the weight of N-vinyl imide at a first elevated temperature and forthwith cooling said mixture to a second temperature lower than said first temperature and maintaining said mixture at said second temperature until polymerization is complete.

8. The method according to claim 7 wherein the N- vinyl imide is N-vinyl succinimide.

9. The method according to claim 7 wherein the N vinyl imide is N-vinyl glutarimide.

10. The method according to claim 7 wherein the N- vinyl imide is N-vinyl-,8-methylglutarimide.

11. The method according to claim 7 wherein the N- vinyl imide is N-vinyl-a-amylsuccinimide.

12. The method according to claim 7 wherein the N- vinyl imide is N-vinyl adipimide.

13. The method according to claim 7 wherein the catalyst is sodium hydroxide.

14. The method according to claim 7 wherein the catalyst is potassium hydroxide.

15. The method according to claim 7 wherein the catalyst is barium hydroxide.

16. The method according to claim 7 wherein the N- vinyl imide is N-vinyl succinimide and the catalyst is sodium hydroxide.

17. The method according to claim 7 wherein the N- vinyl imide is N-vinyl glutarimide and the catalyst is potassium hydroxide.

18. The method according to claim 7 wherein the N- vinyl imide is N-vinyl succinimide and the catalyst is barium hydroxide.

19. The method according to claim 7 wherein the N- vinyl imide is N-vinyl adipimide and the catalyst is sodium hydroxide.

20. The method according to claim 7 wherein the N- vinyl imide is N-viny1-,6methy1glutarimide and the catalyst is potassium hydroxide.

21. The method according to claim 7 wherein the N- 6 vinyl imide is N-vinyl-a-amylsuccinimide and the catalyst is potassium hydroxide.

22. The method according to claim 7 wherein the N- vinyl imide is N-vinyl glutarimide and the catalyst is so- 5 dium hydroxide.

References Cited UNITED STATES PATENTS 15 WILLIAM H. SHORT, Primary Examiner.

H. D. ANDERSON, Assistant Examiner. 

1. AN IMPROVED METHOD FOR THE POLYMERIZATION OF N-VINYL IMIDES TO PRODUCE POLYMERS THEREOF WHICH ARE NOT SOLUBLE IN WATER, WHICH COMPRISES HEATING A MIXTURE COMPRISING AN N-VINYL IMIDE CORRESPONDING TO THE FORMULA 